Slight mis-fire at partial throttle...until I disconnect air temperature sensor

Hi Samuel,
your car should have a fuel-filter that looks like a box. This should be replaced quite often...
Did you check it?

Regards
Norbert

I tested the MAP sensor (both vacuum and resistance) and it passed ok. I also dis a smoke test for leaks... none was found!

I have not tested the injectors, as it is a pain to remove them from my particular car (Citroen DS). But I would think that if there is a problem with the injectors it would manifest itself at all times, right?

Thank you Norbert,

Yes, I replaced the fuel filter last year, but the fuel pump is original and is now over 51 years old.

What are the options available for a replacement fuel pump?
Best
Samuel

I've been waiting until I get to a computer to properly respond.  Glad to see all the Jetronic interest! The people on this site have been incredibly helpful over the years.

I do not have the expertise of some of those that contribute, but I do have more years than I'd care to mention of trial and error on my 73 450SL.  Some thoughts about recent posts:

• As someone else pointed out, the computer dial only affects idle mixture so if your problem is above idle than it is something else.
• If you've got 51 years on a fuel pump I think it can be honorably discharged by now.  Keeping pressure is different than providing volume.  There is a test somewhere (xx ML in yy seconds) that may help prove if that is not the problem, but if a new fuel pump is available I don't think it would be a bad thing to replace.  That is a poke-and-hope, but I saw significant gains after a fuel pump replace (Bosch fuel pump, but it is a newer flavor....dunno if it will work for the Citroen, but if the JetTronic is the same I would think so?) 
• I've gotten my injectors re-built, but didn't see much of a change.
• I had my entire engine wiring harness re-built and that provided significant improvement.  If the computer is getting bad signals, for whatever reason, then it will respond badly. Dunno if that is an option for you.
• Many of the changes, combined, have significantly improved the operation.  The last time I had it out there was very little bad behavior and the temperature sensor was plugged in.  
• I'm still going to hunt for vacuum leaks.  While the tanks will hold for a while, so my door and trunk locks work now, but that doesn't mean there isn't a leak before the tank(s).
• I still have a horrendous hot-start problem.  It is notorious amongst the older 450's, but mine seems worse that I would expect.  Sometimes, I just leave my hood propped open when I park.
• - I'm still chasing gremlins...but they are smaller.

Hi,

I recommend to keep original Bosch D-Jetronic fuel pump as long as it works and does not leak and of course supply enough fuel. I do that myself. I would not follow our unknown friend x046866x. Please sign by firstname as it is usual here. And if you want to discuss your 450, please open a separate thread and let us not mix this one.

 

Apologies for weird username.  That was a poor choice when I registered and I'm contacting some folks that I hope can help me change that...,or I'll create a new one!

My name is Russell Nile.

The reason I chimed in is because I initiated this thread a while ago and when I received a recent notification I chimed in,  If it deserves to be a separate thread because of the difference in the vehicles then someone in the Citroen space will have to initiate that.  I assumed it came here because of a similar problem, but I am not familiar with the D-Jet used on the other vehicles.

Thanks for your help!